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BIOL 230
Roy Turkington

BIO 230 PRACTICE FINAL Colour Used: Person1- Purple Person2- Green Person3- Blue Ecosystem services Services provided by ecosystems and their biodiversity that help sustain human life. Such as pollination, water and air quality, mitigation of droughts and floods, food. Habitat degradation, When the quality of a habitat is decreased for most but not all of the species. For example, pollution Habitat loss The conversion of habitats that inhibits the use of the habitat by wildlife into land for another use, such as farming. Exotic or Invasive species Species that are introduced by accident or on purpose to an area which the species never historically found in. Endemic species A species or group of species that are unique to one area or region Nutrient cycle The movement of nutrients within an ecosystem. Nutrient cycling is never perfect- it has inputs and outputs. These in/outputs are small relative to the amount of nutrients within the ecosystem. Disturbances uncouple cycling. There is a gradient from the poles to the equator. Biogeochemical cycles The physical, chemical and biological transformation and movement of elements and thecycling of nutrients within an ecosystem. Nutrient pool The total amount of element found within the physical or biological component of an ecosystem. Residence time The amount of time an element spends in a pool before if leaves. Weather and Climate Climate is the long term trend of weather over decades for a region. Weather is the day to day variation. Greenhouse effect When molecules (ex. CO2 and CH4) in the atmosphere trap longwave radiation emitted from the Earth’s surface and reemits it back to Earth, causing it to warm. Acid rain Rain that has a pH of 2.0-5.0. Caused by excess SOx, NOx, CO2. Causes damage to lakes, forests and buildings. Biodiversity The variety of life, including the variation of genes, species and functional traits. Includes species richness, evenness and heterogeneity. Habitat fragmentation The break up of a continuous habitat Taxonomic homoginization loss of biodiversity due to the spread of non-native generalists and the reduction of native specialists due to the presence of non-natives. Indigenous species species that are historically found in an area Keystone species a species that has a large affect on an ecosystem relative to it’s abundance. Geochemical The cycling of nutrients between ecosystems Watershed or Catchment A stream that drains all other streams in a terrestrial ecosystem. Can be used to measure input and output rates of nutrients and infer how nutrients are used Turnover rate The replacement of one species with another over time Anthropogenic Human caused. Such as increased C, S, P and N emissions and disturbances like habitat loss, degradation and fragmentation Climate change the directional change in climate over several decades, currently caused by anthropogenic carbon emissions Greenhouse gases Gases in the atmosphere that are in too high concentration compared to preindustrial levels, causing warming of the planet. 1. Explain why some of the world’s most productive forests (tropical rain forests) can persist on some of the world’s poorest soils. The reason is due to the moist, damp, and humid environment, which favors faster decomposition by decomposers and detritivores. Such that since the rate of breaking down litter and dead matter on the forest ground into nutrients is very fast, the tree are able to absorb them; thus, most of the nutrients is within the tree (living biomass). Since there is a low amount of nutrients in the soil this indicates that the trees are taking them up as soon as the nutrients are released from decompositions. Tropical rainforest is humid and warm, favouring high decomposition rates, therefore nutrient turnover is high. Any nutrients released by decomposition is taken up by plants and is stored in the living biomass instead of the soil. In addition, the high biodiversity can cause efficiency in nutrient usage, since a variety of plants can specialize to use different nutrients, hence all nutrients are taken out of the soil. Amount of nutrients in the soil gives no indication of the cycling rate and the actual amount of nutrients within the system. Also, the heavy rainfall in tropical rainforests cause nutrients to leach, making the soil poor. Because the most productive forests such as tropical rain forest have a warm temperature, high precipitation, and high moisture throughout the year, it results in high net primary production and high rate of decomposition. Therefore, it supports high biodiversity communities including many living plants including trees and animals. The soil is poor due to the high numbers of plants and trees that take up nutrients faster than the soil can replenish. Due ideal abiotic conditions, plants and animals usually grow well. Therefore, fallen leaves and animal manure can help replenish nutrients into the system. 2. Would you expect specialist-diet or generalist-diet herbivores to be more strongly affected by spatial patchiness of their plant prey-type(s)? Argue for ONE option only, stating assumptions. -Specialist-diet herbivores would be more strongly affected because if their plant prey is more spatial dispersed it means that the herbivore has to use more energy in order to get to that plant; thus, overall to gain that energy the herbivore must lose energy as well. Assumptions would be that the plant prey are very spread a part. - If patches are small and very spread apart the herbivore isn’t gaining any energy because the amount it eats will be used up by the time it finds a new patch. -Competition b/w specialist of that plant prey would make it more difficult and increase in the usage of energy to find a “fresh” patch, which could be far away. Assuming patches contain different amounts of the specialist’s food and that the food spread apart in a heterogeneous landscape, the specialist diet will be more affected. Generalists can move to any patch and eat any food so food is not limited, therefore if the space is increased between patches, the generalist only needs a longer staying time in that patch. Whereas for specialists, their food source can be limited within patches. Therefore if space between patches increase, and the specialist may not have enough food in that patch to compensate the longer travel time, causing the specialist to decrease the net gain in energy. Specialist's diet would be more affected with the following assumption: - patches contain a variety of food so resources that a specialist can consume are limited whereas a generalist can intake almost all the resources that a patch provides - the specialists are the first foragers arriving at the patch that hasn’t been grazed before. - the patch spacing is consistent and no net energy gain during travel time. Because the staying time is shorter for a specialist is much shorter than a generalist, the distance between the patches have to be shorter for a specialist to reach otherwise specialists won’t survive. 3. In some ways – especially by consuming only small portions of the live host/prey, rather than killing it first – parasites on (or inside) animals are analogous to herbivores on plants. Does this imply that parasite abundance is controlled by predation, in the manner suggested for the control of herbivores by HSS theory? Make EITHER a “yes” OR a “no” argument (not both), and state assumptions. -No they are not controlled by predation because parasites need to compete with other parasites in order to get a host to live in/on. There isn’t unlimited host supply as there is an unlimited food supply (plants) for herbivores. - Predation wouldn’t control there abundance because assuming no animal eats parasites as a food supply. -Predation of herbivore with parasite would mean that the predator would now be the host for the parasite Assuming there is only one or a few parasite to one host so the host does not die. No, because unlike in herbivory, which is supplied by an unlimited plant population, animal hosts are much less abundant. Therefore, because there is a relatively less amount of food supply for parasite compared to herbivores, parasites should be controlled by competition for a host, not by predators. No, they are not controlled by predation. Assuming that there is a limited amount of hosts/ animals, parasites have to compete with one another for a host to live in/on. In HSS theory, we assume that there is nearly unlimited supplies of resources (ex. plants) for the herbivores. Plants are unlimited for herbivores but it is not true to say animals are unlimited for parasites to live on/ in. Therefore, it is competition, not predation that controls parasites on animals. 4. Name and briefly explain three physical consequences on the world resulting from climate change. 1. There would be an increase in sea level by +25cm which consequently could mean islands would disappear into the ocean (Maldives) and so would most sea-level areas (Richmond, New York, London). Displacement of 1000s of people with no homes. Most of these sea-level areas are major portsà economic consequences 2. Increase frequency of extreme events such as heat wave, heavy rain, increased droughts, increase in hurricanes, floods, and forest fires. Consequently these damages would have immense impact of the economy, on the ecosystem ( frequently being disturbed → not enough time to mend the damages), and increase in deaths. 3. There would be 3 degree increased in temp at the equator and a 5-8 degree increase in temp at the poles. Increase in temp at the poles would cause increase amount of glacial melting; thus, an increase of sea levels and decreases glacial surface areas which means less hunting ground for polar bears. Also warmer temps in water could cause a decrease in fish population (trout, salmon, etc.) b/c they require cold water to survive. 1. Global temperatures will increase as greenhouse gases warm the planet. Temperature is project to increase 3C in the tropics, 5-8C at the poles and globally, 1.8-4C. 2. Increased sea levels due to melting of polar ice caps. It is projected that there will be 25 cm increase in sea level by 2100. Many places below sea level, like the Maldives, Richmond or Baghdad will be submerged. 3. Animals and plants are affected as well. In some areas, causes earlier spring green, earlier bird migrations, death of 4% of lizard species and projected that 20% decrease by 2050. 1. Rise in sea level: due to the increase in temperature, the glaciers and ice caps are melting causing the sea level to rise. 2. Global temperature increase: due to increase in greenhouse gases produced through industrial activities, burning fossil fuels and increase in CO2 emission. 3. Animal responses: results in habitat loss, fisheries decline, range change (dispersal), change in time for migration, breeding season. 5. Briefly explain (a diagram could help) why tropical forest vegetation may be more vulnerable to climate warming than boreal forest vegetation In temperature increases, respiration will be favoured in the Tropics (ie. when respiration is above photosynthesis). Respiration causes a net loss in energy in plants, therefore if plants switched to respiration for a prolonged period, they will die. However, if temperatures increased, Boreal forests would still favour photosynthesis, therefore will be less affected. Note: my answer is completely different... and I feel like I’m off... your explanation makes sense The decomposition rate and nutrient cycling is going to be faster the the climate is warming. Due to the location, abiotic factors of the tropical forests, the soil temperature is warmer here than boreal forests. The mean residence time for tropic is going to be even faster than before, especially the time for nutrients like nitrogen and phosphorus is so much lower compared with boreal forests. Climate warming will act on boreal forests eventually but just much slower than it will act on tropical forests due to its already fast rate of decomposition. - Tropical forest vegetation would be more vulnerable due to as temperatures increase the rate of photosynthesis decreases thus, the rate of respiration increases. If the temperature increases to a very high amount and extended amount of respiration could cause tissue deterioration of the plant and potential death of plants. In addition, as temperatures increase the amount of moisture would decrease consequently. Without enough moisture (water) plants would not be able to photosynthesize properly. 6. Explain briefly how diet-switching by a foraging animal population could relate to prey diversity (and/or biodiversity) in the area occupied by that forager-population; your answer will demonstrate an understanding of frequency-dependent selection. Forager switching can cause higher biodiversity because foragers that are non-selective will eat whatever prey is at highest density (frequency dependent selection). By doing this, the population of prey species on which it feeds will be kept under control so no one species dominates other species, thus promoting coexistence and increases biodiversity. A foraging animal switches diet because they discover accidentally that their diet allows a new kind of prey and it’s high in density. A foraging animal controls the prey density and by diet-switching, it doesn’t drive the prey before diet-switching to extinction. Therefore, it increases biodiversity. -Diet switching is a frequency dependent predation because the foraging animal prefers consumes the most abundant/common prey. Thus the foraging animal increases its preference for a prey as the prey becomes more abundant. - It relates to prey diversity because a foraging animal does not have a specific diet; thus, it will eat prey that is more common at that time and will switch its diet as that prey’s density becomes low. In other words, the forager does not eat the prey population until extinction. By diet-switching it reduces the chances of one population to be eaten until extinction; thus, increasing the biodiversity. 7. Some prey animals (like our old lab friends, terrestrial isopods) are largely protected from predation because they secrete in their tissues bad-tasting, mildly-poisonous chemical compounds... but this has not allowed them to breed uncontrollably and become superabundant, so the benefit of protection must also have a cost. Suggest ONE specific cost of this protection-bytoxicity benefit; state your cost-idea in the form of a testable hypothesis deriving from theory, and state assumptions. Assuming energy resources are limited for isopods, isopods allocate their energy towards producing the toxins, leaving very little energy left for reproduction. The energy invested in isopods focuses more on producing toxins than on reproduction. If we assume energy usage is very limited for the isopods, then isopods will not have energy to reproduce once they invest and use most of energy on toxin production. - Terrestrial isopods use the majority of their energy towards protecting themselves (producing poisonous toxins) and not enough energy is devoted for reproductive purposes. - Assuming that the isopods only have a limited amount of energy that they only use towards protecting themselves and for reproduction. 8. Some predators (such as baleen whales, and web-building spiders) exhibit a style of prey- capture behaviour known as a Type 1 functional response (as illustrated in the graph at left). a. Describe in biological (not mathematical) terms the behaviour of a Type 1 forager as shown on the graph. (5 marks) The forager is non-selecting, meaning the feeding happens at a rate proportional to the amount of prey available. Eventually levels off because the feeder reaches maximum feeding capacity (ie. it cannot eat any faster or any larger amount at this point) Predators exhibit typical filter-feeder. As the prey density (N) increases, the number of prey caught in a given period of time increases until it reaches a certain N that the graph just levels off. The leveling-off happens when the feeding capacity reaches maximum. - The number of prey caught in a certain amount of time (Ne) increases as the prey density in the area (ex. Filter feeders mouth) increases. As the graph plateaus it indicates that the filter feeder has reached the maximum it can capture/ eat and thus it reaches its maximum capacity (its gills become clogged and can no longer capture anymore plankton) and swallows. Once the filter feeder swallows if starts back at zero. -Whatever was caught does not reflect the filter feeders hunting skills… It reflects the richness of the habitat. b. In any type of functional response (Types 1, 2, or 3), there is always a “plateau” number of prey caught when N is high; why? (5 marks Plateaus because the forager has a limit to the amount it can eat (ie. it becomes full).Even though the number of prey increases, foragers cannot continue to feed at a rate porportional to the amount of prey because it cannot catch/consume the prey at a faster rate. The situation shifts from forager being limited to amount of prey, to forager being limited by the amount the predator can catch/eat Because there is only so much that the predator can consume, there is a limit to its feeding capacity. Even when the prey density increases, the predator’s ability and maximum capacity for consumption of resources don’t change. - The plateau indicates the maximum capacity the organism can consume. This is the point where the organism can no longer take in more / too full to eat. -Even with the increase density of prey the predator cannot eat anymore b/c it has reached its maximum. 9. One proposed explanation of high species-richness in the Tropics compared to other areas of the Earth is the “Productivity Hypothesis”. a. describe briefly the mechanism by which the Productivity Hypothesis is supposed to work (4 marks). Productivity hypothesis states that because the tropics have high productivity, it also has high diversity of food and species will specialize to eat the food, causing speciation and higher biodiveristy. Higher productivity also leads to increased coexistance because there is less competition for food and decreased extinction rates, causing high biodiversity. Productivity hypothesis suggests that there is a high species richness and high productivity in the tropics that support diverse communities because of its pleasant conditions for growth and survival throughout the year. Plants are productive, as are the organisms consuming them so plenty of food for all consumers in food web, therefore, it promotes coevolution while keeping biodiversity high. - Productivity hypothesis is an ecological mechanism. Such that areas, like the tropics, have good producing conditions (high rainfall); thus, have a high level of productivity (growth of plants) for consumers to eat. There is enough for new species to immigrate into these areas as well maintain the species richness that it already has (extinction rate is low). There is enough vegetation for lots of species to eat. b. is the Productivity Hypothesis a deterministic or a stochastic theory? Select ONE choice, and justify (6 marks). It is deterministic because ecological principles state that with large amounts of food source, competition decreases to allow coexistance. Also. species will partition resources to avoid niche overlap by the competitive exclusion principle, therefore causing speciation. All these events, although not always inevitable in all ecosystems, can be a consequence of high productivity. The productivity hypothesis never mentions any events that can be stochastic, such as disturbances and the climate of the tropics is stable. It is deterministic because the climate and conditions don’t usually change or fluctuate much, it is determined for that particular area. Because productivity is high, it has plenty of food for consumers in food web, leading to decrease in competition, increase in coexistence and high species richness: - predators become diverse and numerous, keeping the prey abundance low. Species held down to low densities are unlikely to be driven to extinction by competition or - predators can persist even if they are specialized because food supply is steady, leading to diverse predators with little niche overlap are unlikely to be driven to extinction by competition It is deterministic theory because the abiotic factors that influence high productivity (enough vegetation for consumers to eat and immigration of new species into the area) is not due to random chance.Abiotic factors such as temperature and rainfall are determined by where the area is located in the world (areas near the pole would have low productivity). The coexistence of new species and existing ones are determined due to the high productivity of vegetation; thus, species may not have overlapping niches and would not be driven to extinction due to intense competition against species for resources. 10. In order to avoid constructing an expensive addition to a city’s wastewater treatment plant, a city engineer suggests that after removing suspended solids and noxious chemicals, the wastewater could be spread on a scrub forest and permanently solve two major problems. He reasoned that the remaining organic matter in the wastewater would be broken down by decomposers (e.g. soil fungi and bacteria), and excess inorganic nutrients would be taken up by forest plants, thereby preventing eutrophication (i.e. overfertilizing) of a stream which currently received the nutrients. Aside from aesthetic considerations, where has the engineer gone wrong in his thinking? (10 marks) -overfertilization of terrestrial ecosystem -terrestial forest cycling could also be saturated therefore further inputs of nutrients might exceed the rate of cycling, therefore causing these elements to turn into compouds like N2O, CO2 or CH4, which are greenhouse gases -Plants can’t take up inorganic nutrients- they must be turned into usable forms first -decomposition and cycling rates might not be able to keep up with the rate of our input -if decomp/cycling rate cannot be kept up with, then there will be nutrients in runoff and eutrophication of aquatic ecosystems -the process of adding waste water to forests could cause disturbances, which uncouples nutrient cycling -plants might be adapted to low nutrient levels, so if you increaes nutrient levels these plants may be out competed -can cause acidification in the case of excess N deposition -does not consider what will happen to wildlife habitat - Plants do not take up inorganic nutrients, these nutrients needs to be broken up in order for the plants to absorb them -Also, if the engineer was planning to dump the organic matter in the wastewater in a random forest without considering decomposition rate it could cause problems. Decomposition may not be ideal in that particular area; thus, there would be an accumulation of this matter that cannot be broken down for plants to absorb. In addition, if that forest is already high in nutrients in both the soil and in the living biomass, the inorganic/organic matter would accumulate and possibly seep through the soils into ground-waters (aquifers) and cause eutrophication of a stream. -The inorganic nutrients could possibly still be harmful to organisms and plants. Example excess sulfur and nitrogen in high concentration would be harmful for living life-forms. If these inorganic nutrients seeped into underground waters could be harmful to marine organisms (fish). 11. Suppose that a “pulse” of nutrients was added to a lake in each of two consecutive years. In both years, measurements of nutrient pool sizes in the phytoplankton, herbivores, predators and detritivores were made 1 week before and 1 week after the pulse. Offer an explanation for the following observations made one week after the pulse was added (note: “increase”, “decrease”, and “no change” refer to the observed changes compared to the pre-pulse conditions for that particular year): • Year 1: phytoplankton and detritivores both increase, but no change in herbivores and predators. • Year 2: Phytoplankton and herbivores both decrease, but predators and detritivores both increase. Originally, the prey density (phytoplan
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